摘要
AgNbO_(3)具有反铁电性及高的极化强度,在智能器件领域有着重要的应用前景.本文采用助溶剂法合成了高质量的AgNbO_(3)单晶(最大尺寸5 mm×4 mm×4 mm),系统研究了其相转变特征、光学和电学性能.当AgNbO_(3)晶体处于正交M相时,保持着相同的畴结构;由M_(2)相转变至地相时,偏光显微镜(PLM)照片衬度变暗,同时电导率和介电损耗明显上升.当AgNbO_(3)单晶由M_(3)相到顺电O相时,畴结构消失;同时,表现出明显的热滞后现象,属于第一类相变.室温下,AgNbO_(3)单晶的直接带隙拟合禁带宽度为2.73 eV,略窄于AgNbO_(3)陶瓷.在临界电场以下,AgNbO_(3)单晶表现出更高的电致应变(0.076%,E_(m)=130 kV/cm).在绿色激光照射下,介电常数由70增至73,表现出明显的光致介电效应.
AgNbO_(3),with the antiferroelectric ordering and huge polarization(>50μC/cm^(2)),has potential applications in smart electronic devices,such as energy storage dielectrics,large displacement actuators,and electrocaloric cooling device.Large electro-strain and excellent energy storage properties have been reported in AgNbO_(3)-based ceramics.Nevertheless,the lack of systematic research on the AbNbO_(3)single crystals increases the difficulty in further understanding their structure-property relationship.In this work,<001>c oriented AgNbO_(3)single crystals with a large size(maximum size 5 mm×4 mm×4 mm)and high quality are successfully grown by the flux method.The phase transition characteristics are studied by the X-ray diffraction,temperature dependence of dielectric data and AC impedance,polarized light microscope photos,and differential scanning calorimetry curves.The electrical and optical properties are studied by the ferroelectric response and electro-strain response,optical absorbance spectrum and photo-dielectric effect.The AgNbO_(3)single crystals with the M phase exhibit the same domain structure.When the structure changes from M_(2) to M_(3),the contrast of the PLM image is darkened.Correspondingly,the conductivity and dielectric loss significantly increase,which relates to the dynamic behaviors of the carriers.Interestingly,neither exothermic peak nor endothermic peak relating to the M_(2)-M_(3) transition is observed.The active energy for the M_(3) phase AgNbO_(3)single crystal is~1.24 eV.When the structure changes from orthogonal M_(3) to paraelectric orthogonal O,the domain structure disappears and the contrast becomes darker.The finding indicates that the anisotropy of the crystals disappears.At the same time,an obvious thermal hysteresis observed in the DSC curve reveals that the M_(3)-O transition is first-order.At room temperature,the direct band gap of AgNbO_(3)single crystal is~2.73 eV,which is slightly narrower than that of AgNbO_(3)ceramic.Below the critical electric field,AgNbO_(3)single crystal shows an electro-strain of 0.076%under E_(m)=130 kV/cm.The obtained electro-strain value is much higher than that of AgNbO_(3)ceramic under the same electric field.The relative permittivity increases from 70 to 73 under the green laser irradiation,showing an apparent photo-dielectric effect.We believe that our study can assist in the further understanding of the phase transition characteristics and physical properties in AgNbO_(3)single crystals.
作者
牛佳林
董思远
魏永星
靳长清
南瑞华
杨斌
Niu Jia-Lin;Dong Si-Yuan;Wei Yong-Xing;Jin Chang-Qing;Nan Rui-Hua;Yang Bin(Shaanxi Key Laboratory of Optoelectronic Functional Materials and Devices,School of Materials and Chemical Engineering,Xi’an Technological University,Xi’an 710021,China;Shaanxi Coal Chemical Industry Technology Research Institute Co.Ltd,Xi’an 710070,China;High-tech Research and Development Center,Ministry of Science and Technology,Beijing 100044,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第3期291-298,共8页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11704301)
陕西省自然科学基础研究计划(批准号:2022JM212)资助的课题。
